My InterpretationI'm probably completely off-base, but I get the impression that this is about a couple whom the general public doesn't like to see out together and thus stays home when they want to be together. "I can't seem to take you anywhere" "the rank and file shoot us dirty looks"

"The night time here is a plastic box, gently amplified in the basement rock." Maybe they have a basement apartment? Wherever they are, they hear distant voices. Then the narrator says that "when you're not around, this is our sound." By this she may mean that when her significant other is not with her, she and her friends sound just like those distant voices. They're outside, at night, presumably having a good time.

In the next verse, the couple goes out again, to a different square, and again has to leave their friends while the "rank and file" shoot them dirty looks. The narrator tells her SO to call a taxi since she doesn't want to walk back. That she has to ask implies that they could have walked home from where they were, but she preferred not to. The reason for that could be that she doesn't want to deal with more "dirty looks" or she feels those looks might escalate into something more dangerous. Or maybe she's just lazy; I don't know.

Finally, "this is not a song, because there's nothing wrong when the light inside is not as bright." She wants to be outside with friends, where things are brighter, but she's stuck inside. Still, she reassures her SO that there's nothing wrong. It's not really their fault at all.

As for why people don't want to see them together, there are a couple of potential reasons: 1) they're a lesbian or interracial couple in a repressed area 2) the SO has a very public negative reputation. or, 3) the SO actually behaves horribly in public, and the people shooting them dirty looks are completely justified.